The present invention relates to a protective apparatus for secondary batteries.
Secondary batteries have been used as a power source of such electronic devices as video cameras and headphone stereo equipment. As these electronic devices are gaining more in capability while being made smaller in size, there is a growing demand that their secondary batteries provide higher energy density.
This requirement is being met by the ongoing development of nonaqueous electrolyte secondary batteries. These are batteries that use as their anode the lithium metal, lithium alloy, or a carbonaceous material that allows lithium to be doped and dedoped.
One disadvantage of the nonaqueous electrolyte secondary batteries is that when they are left in an atmosphere whose temperature is higher than room temperature, the batteries tend to lose their capacity because of degradation in the electrolyte and/or in the active material thereof. Thereafter, the batteries fail to recover their initial capacity following a sufficiently long recharging process.